This invention pertains to a generator apparatus driven by an internal combustion engine to charge battery by an output of an AC generator driven by the internal combustion engine.
A generator apparatus driven by an internal combustion engine to charge a battery by an output of an AC generator driven by the internal combustion engine comprises a revolution controller to control a revolution of the internal combustion engine so as to maintain a deviation between a actual value of a terminal voltage of the battery and a desired value thereof or restrain the deviation to an allowable value or less whereby the terminal voltage of the battery is generally maintained at the desired value thereof.
In order to save a fuel consumed by the internal combustion engine driving such a generator apparatus, the internal combustion engine is preferably controlled to start and stop so that the engine starts when the battery is required to be charged while the engine stops when the battery is perfectly charged.
In order to make such a starting control of the engine and a stopping control thereof, it will be thought out that the engine should start when a detected value of the terminal voltage of the battery is lowered to a first set value indicating a condition in which the engine should start for charging the battery while it should stop when the detected value of the terminal voltage is elevated to a second set value (higher than the first set value) indicating a condition in which the battery is perfectly charged.
However, in case that the revolution controller is provided which controls the revolution of the internal combustion engine so as to maintain a desired value of the terminal voltage of the battery, if the second set value for controlling the stopping of the engine is so set at higher than the desired value of the terminal voltage, then the battery will be disadvantageously overcharged because the internal combustion engine cannot be stopped.
Reversely, if the second set value for controlling the stopping of the engine is so set at a value less than the desired value of the terminal voltage, the battery will be disadvantageously undercharged because the engine is stopped before the battery is perfectly charged.
It will be thought out that, in order to solve such problems, the engine is adapted to be stopped when a detected output current of the generator reaches the designated value or less. However, since this requires a current detecting resistor or a current detecting current transformer to detect the output current, the apparatus will be disadvantageously more expensive in comparison with that detecting the terminal voltage.
Accordingly, it is an object of the invention to provide an internal combustion engine driven generator apparatus adapted to make a control of engine starting and stopping operations without any requirement of detection of an output current of a generator and without any undercharge and overcharge of a battery whereby a consumption amount of fuel can be saved.
The present invention provides a generator apparatus driven by an internal combustion engine and comprising a revolution controller to control a revolution of the internal combustion engine so as to maintain a deviation between a terminal voltage of a battery which is charged by an output of an AC generator driven by the internal combustion engine and a desired value of the terminal voltage or restrain the difference to an allowable value thereof or less, and engine state controller to make a starting operation of the internal combustion engine when the terminal voltage of the battery is lowered to a set start voltage and an engine stop controller to make a stopping operation of the internal combustion engine when the revolution of the internal combustion engine is lowered to a set stop revolution.
What xe2x80x9cstart voltagexe2x80x9dmeans is a voltage with which the battery should start to be charged by starting the engine. What xe2x80x9cstop revolutionxe2x80x9d means is a revolution with which the battery is perfectly charged and therefore the engine may be stopped.
As aforementioned, with the engine start controller provided for making a starting operation of the internal combustion engine when the terminal voltage of the battery is lowered to the start voltage and with the engine stopping controller provided for making a stopping operation of the internal combustion engine when the revolution of the internal combustion engine is lowered to the set stop revolution, the internal combustion engine can be started so that the battery is charged when the terminal voltage of the battery is lowered to the voltage with which the battery is required to start to be charged. The internal combustion engine can be stopped when the battery is perfectly charged and therefore the revolution of the engine is lowered to the stop revolution.
In this manner, according to the invention, since the internal combustion engine is adapted to be started when the terminal voltage of the battery is lowered to the predetermined start voltage and adapted to be stopped when the revolution of the engine is lowered to the stop revolution, the start and stop of the engine can be controlled without detecting any output current of the generator by using an expensive current detector means such as a current transformer whereby the fuel consumption can be saved.
In the invention, the engine is stopped when the detected revolution of the engine is lowered to the set stop revolution, but in case that the revolution of the internal combustion engine is so controlled that the deviation between the terminal voltage of the battery and the desired voltage thereof should be restrained to the allowable value or less, since the revolution of the engine is lowered as the charge of the battery advances, the battery can be effectively prevented from being undercharged in the condition that the stop revolution is so properly set when the starting and stopping operations of the engine are controlled.
In the invention, the stop revolution should be preferably adjusted in accordance with the magnitude of the loads connected to the battery. More particularly, if the loads of the battery are relatively smaller and therefore it is hard for the battery to be in the condition of being undercharged, the stop revolution of the engine can be set at a higher value while if the loads connected to the battery are relatively larger and therefore it is easy for the battery to be in the condition of being undercharged, the stop revolution should be set at a lower value. In this manner, the engine can be prevented from being wastefully operated whereby the fuel can be saved and noise can be reduced.